10,979 research outputs found

    A synopsis of the weather problems facing today's general aviation pilots

    Get PDF
    Concentration on weather to data has primarily been at the point of observation. There have been efforts to obtain and disseminate en route weather through pilot reports (PIREPS), but the efforts have been meager. What is needed is the cooperative efforts on the application of technology to the acquisition and dissemination of the en route weather data for those pilots in the air as well as those who are flight planning on the ground. A comprehensive three-dimensional computer storage system is proposed that receives weather information from all aircraft on IFR flight plans and stores this information by altitude and geographic coordinates. Also, a report on the Federal Aviation Administration's Research Engineering and Development Aviation Weather Program from the aspect of past, present and future is given

    Protective encapsulation of implantable biotelemetry units

    Get PDF
    Development of materials for encapsulating electronic devices used in biotelemetry is discussed. Chemical resistance of materials to effects of animal fluids is described. Silicone rubber is recommended as basic material with polymers applied to outer surface for protective coating

    A Construction of Killing Spinors on S^n

    Get PDF
    We derive simple general expressions for the explicit Killing spinors on the n-sphere, for arbitrary n. Using these results we also construct the Killing spinors on various AdS x Sphere supergravity backgrounds, including AdS_5 x S^5$, AdS_4 x S^7 and AdS_7 x S^4. In addition, we extend previous results to obtain the Killing spinors on the hyperbolic spaces H^n.Comment: 11 pages, LaTe

    General Kerr-NUT-AdS Metrics in All Dimensions

    Full text link
    The Kerr-AdS metric in dimension D has cohomogeneity [D/2]; the metric components depend on the radial coordinate r and [D/2] latitude variables \mu_i that are subject to the constraint \sum_i \mu_i^2=1. We find a coordinate reparameterisation in which the \mu_i variables are replaced by [D/2]-1 unconstrained coordinates y_\alpha, and having the remarkable property that the Kerr-AdS metric becomes diagonal in the coordinate differentials dy_\alpha. The coordinates r and y_\alpha now appear in a very symmetrical way in the metric, leading to an immediate generalisation in which we can introduce [D/2]-1 NUT parameters. We find that (D-5)/2 are non-trivial in odd dimensions, whilst (D-2)/2 are non-trivial in even dimensions. This gives the most general Kerr-NUT-AdS metric in DD dimensions. We find that in all dimensions D\ge4 there exist discrete symmetries that involve inverting a rotation parameter through the AdS radius. These symmetries imply that Kerr-NUT-AdS metrics with over-rotating parameters are equivalent to under-rotating metrics. We also consider the BPS limit of the Kerr-NUT-AdS metrics, and thereby obtain, in odd dimensions and after Euclideanisation, new families of Einstein-Sasaki metrics.Comment: Latex, 24 pages, minor typos correcte

    Gamma-ray emission associated with Cluster-scale AGN Outbursts

    Full text link
    Recent observations have revealed the existence of enormously energetic ~10^61 erg AGN outbursts in three relatively distant galaxy clusters. These outbursts have produced bubbles in the intra-cluster medium, apparently supported by pressure from relativistic particles and/or magnetic fields. Here we argue that if > GeV particles are responsible then these particles are very likely protons and nuclei, rather than electrons, and that the gamma-ray emission from these objects, arising from the interactions of these hadrons in the intra-cluster medium, may be marginally detectable with instruments such as GLAST and HESS.Comment: 8 pages, 4 figures, accepted by MNRA
    • …
    corecore